Uhhh, no. Polyester is an organic polymer. So is cellulose for that matter. Polyester is long chains of ester molecules (which are organic). As for purity, that depends on whether there are traces still present of the chemicals used during manufacturing and processing. Hopefully there are none, but unless there's a way to get that data you really want to be sure you wash the stuff real well. It's not made for a food application so there's no telling what chemical traces may remain.

I washed the deuce out of the stuff, yeah. My biggest concern, as with all "reusable" items (including stock Aero filters) is the extent to which they act like a petri dish. A stock Aero filter dries out before it can begin hosting raucus bug parties, but this felt stuff doesn't dry so quickly. A dash of boiling water after rinsing seems a sane hedge, and before using as well. A sniff with the nose, too, I guess.

Sure. Coarser grind -- but also, I'll try a coarser filter. I have some 25 micron fabric. I anticipate fines, but what the heck. I'll also do a 5 micron with a coarser grind -- I'll use the FP setting on my SMP.

Rats, still haven't gotten around to doing this. Sorry. Will try to this weekend. Actually, I promised Alan I'd do some testing, since I have 5# of Robusta I'll be breaking a new roaster in with, and I'll take it far enough to yield plenty of oils in the cup. Needless to say I won't be drinking the dreck, but it should be perfect for testing. My problem will be measuring! Geez.

OK, I'm driving over to McMaster to get a big sheet of the stuff. They're on my way out today anyway. ;-)

Geez, I just bought stainless perf for my new drum roaster from 'em the other day.

Park a polyester or fine metal filter (using paper moots this procedure) in the Aero's cap, and set aside.

Push the plunger into the Aero body about an inch, and set the inverted the Aero on the counter/table. Pour in a half inch of water. Add your grind. Add more water, leaving room for bloom. Stir like heck as usual for an Aeropress.

Carefully mount the cap atop the Aero (still inverted) and press in that position. Extraction will pass through the holes and begin to swell atop the inverted cap; deftly tip this into a cup before it rolls of the cap and spills all over the table. Repeat until there's no air in the Aero. This will capture your oils.

"Re-vert" the Aero over the cup, and press normally. Shortly before the puck begins to form, pull the plunger up (but only if you're using the polyester!) and air will gurgle through. Press, now that there's air, until the puck gets air going through it.

If you wish, withdraw the plunger yet again, pour in a bit more water, and press it through. But the wisdom of that depends on how far extraction has proceeded for the grind.

That's it. This will yield a very rich, complex cup.

For this, I recommend a hotter and slightly more coarse grind (drip grind, more than espresso grind). However, a fine grind won't clog the polyester a bit; you just need to move more quickly.

Backflush the filter when finished, and set aside for re-use. Peroxide the thing, I think, from time to time.

It sounds rather more complex than pressing normally, and I'm unsure of where to get those types of filters for the Aero. I gathered from the thread that they aren't commercially or easily available, and I suck at modding things. Alas; I wanted to taste that cup.

It sounds rather more complex than pressing normally, and I'm unsure of where to get those types of filters for the Aero. I gathered from the thread that they aren't commercially or easily available, and I suck at modding things. Alas; I wanted to taste that cup.

OK, the stuff is not FDA approved. I kind of knew that, but hey. McMaster didn't give any information about approved alternatives, so I just inquired at about 6 other companies who have several FDA-approved products. We'll see what comes of it.

I'll continue to use the material for myself, but I reckon I won't use it at the farmer's market on customers. ;-)

Now to hack the Aeropress itself, to make inverted pressing a plausible and sane option.

OK, the stuff is not FDA approved. I kind of knew that, but hey. McMaster didn't give any information about approved alternatives, so I just inquired at about 6 other companies who have several FDA-approved products. We'll see what comes of it.

Yep, that's what bothers me. Plastics are kept flexible by the addition of volatile chemicals. These chemicals come out of the plastic over time. That's why it gets hard and cracks when exposed to sun and heat. I'd be really surprised if some of those chemicals aren't "extracted" from the polyester by the hot water. I'd also expect the natural oils in the coffee to help dissolve them.

If they make a food grade polyester, I'd be happy to try it. Otherwise I think I'd prefer to err on the side of caution. There are some very nasty solvents used in the production of plastics. If you want the coffee oils, I think it would be prudent to stick with a gold filter and put up with the sediment until you can find a MSDS for the polyester you've chosen.

I wouldn't use recycled paper as a filter for exactly the same reason - you don't know what chemicals were used in its processing.

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